Green Mountain replacement barrels

[ryoung14]

Just ordered a Green Mountain drop-in .54 cal., 1-70" Twist, 15/16" across-flats barrel for my .50 Hawken. It's 32" long and, with the slow twist, is obviously a roundball barrel. Was wondering if anyone has had any experience good or bad with this barrel and if anyone has a load that works particularly well.

BTW, Green Mountain has fast-twist stainless .50 Hawken & Renegade replacement barrels on sale right now at about half price, if anyone's interested. I have a fast twist GM blued barrel for the Hawken that shoots well, but lately I've become more of a roundball shooter.
http://www.gmriflebarrel.com/

Bob

 

[wtilenw]

I have 2 of these barrels. One in .54 and one in .58. They are both excellent shooters. I use 80 gr in the .54 for targets and 90 grs. for hunting. The .58 I have only tested 90 grs. and it is very accurate. I'm using Pyrodex select though. Havn't tested real black yet. I think you will be very happy with it.
Idaho PRB

 

[roundball]

I don't have a .54cal in GM, but do have a GM .58cal x 1" x 1:70" Flint RB barrel as a drop in to the large size TC Hawken stock...extremely accurate.

My .54cal RB barrel is TC's 15/16" x 1:66" for their regular size TC Hawken...also extremely accurate.

 

[cliff mccann]

I bet you're gonna love that barrel!I'm using 110 grains of GOEX Ffg under a Hornady .535 ball with a TC .015 lubed patch,and a CCI cap.Shoots into one hole at 50 yards,and 1 1/2" group at 100 yards.My rifle liked every charge from 80-110 grains,but not 120 grains as much.I find it very helpful to accuracy to run a single dry patch through the bore AFTER seating the ball,but BEFORE capping the rifle.

 

[Donny]

I bought same, and I wasted my $. I cannot get the GM rb barrel to shoot well without heavy loads, and these make me flinch after a few shots. A days shootin ain't fun. The old T/C 1/48", which was somewhat pitted,used and abused, shot better and was more accurate, and I could target shoot well all weekend with 30-50 gr. loads. I thought the 1/70 slow twist was supposed to be the cat's meow for rb, it may be, but not for me.

 

[roundball]

I bought same, and I wasted my $. I cannot get the GM rb barrel to shoot well without heavy loads, and these make me flinch after a few shots. A days shootin ain't fun. The old T/C 1/48", which was somewhat pitted,used and abused, shot better and was more accurate, and I could target shoot well all weekend with 30-50 gr. loads. I thought the 1/70 slow twist was supposed to be the cat's meow for rb, it may be, but not for me.

That's surprising...I've used 70,80,90, and 100grns Goex 2F in mine and they're all as accurate as the other...I normally use Hornady .570's...this morning I tried some Remington .570's and they did fine too.

70grns Goex 2F and .015" prelubed plain cotton patch is OK, but if I use 80/90/100 grns 2F, I use an oxyoke wonderwad over the powder, and .018" pillow ticking patches.

You could try wads and see if they help...or maybe a thicker patch...

 

[ryoung14]

:hmm: Donny, your experience shooting light RB loads with the TC 1-48" twist barrels is about the same as mine. They shoot RB like a dream with light loads. My favorite target load for a .50 is .490 RB in a .010 Ox-yoke wonder patch over 30 gr. of Pyrodex P. The Hawken, the Greyhawk and the 1-28" Black Mtn. Mag. all love that load. They'll shoot like .22s all afternoon without cleaning or significant recoil. Loading is easy and the patches look almost good enough to reuse.

Things get spotty, however, when the powder charge is upped to something you would hunt big game with. I always attributed it to the "too-fast-for-RB" twist and the shallow TC rifling. But it may be that I just didn't spend enough time working up a load. My slow twist 1-66" GPR, on the other hand, shoots very well with full power loads but doesn't do well with the light .30 gr. load.

It does make sense, however. The spin imparted to the ball is what stabilizes its flight. In any given barrel, the rate of spin should be proportional to the ball's velocity at the muzzle. The lower the ball's exit velocity the slower the spin IN THAT BARREL.

There is probably some threshold below which the spin is insufficient for stability. A fast twist barrel would reach that stability threshold at the lower ball velocities reached with light loads. With heavy loads, the spin should be well above the stability threshold but, instead, the shallow TC rifling begins to lose its grip on the ball as velocity and rate of spin increase. Without a really tight and tough patch accuracy deteriorates.

The slow twist RB barrel, OTOH, needs a full power load to reach the spin-stability threshold. In addition, it's deep cut rifling hangs onto the ball until the end. The result is good accuracy with full power loads....what I'm looking for.

Well this certainly got too long. :m2c: and then some. It's the way I've got it figured anyhoo. Feel free to shoot this full of holes, anyone. I'm here to learn.

:thanks:, everyone, for the load info and encouraging words. I'll report back on this barrel when I've shot it some.
Bob

 

[roundball]

I've seen a lot of conjecture about PRB accuracy in 1:48's vs. slower twist barrels over the years, and last summer I realized I had everything I needed to personally run side by side tests.

I spent three Saturdays at my range with TC 1:66" and 1:48" barrels in .45, then .50, then .54...same components, cleaning procedures, weather, shooter, etc...same everything...alternating one rifle then the other.

TC's 1:48" standard barrels shooting the same full power 1:66" PRB hunting loads gave outstanding accuracy to the point where if someone had shuffled the targets together, I would have had to pause and study them to assume which were made from which barrel.

1+7/8" - 2+3/4" groups at 100yds from 1:48" twist barrels is fine accuracy in my mind, and I'm sure that variance is due more to my eyes and shooting ability than from any worry about twist...I think far too much blind acceptance is given to the 1:48" RB accuracy topic...IMO, it's an old wives tale that just keeps being repeated.

My hunting loads used in the tests:
90grns Goex 3F
Oxyoke wonderwads
TC .018" prelubed pillow ticking
Hornady .440/.490/.530 balls
TC Hawken 28" x 1:48" Flintlock barrels
TC Hawken 32" x 1:66" Flintlock barrels
100yds bench rest

:front:

 

[ryoung14]

Yep, I'd be content with those groups, Roundball . I'll bet those .018" ticking patches had alot to do with it. I haven't used those much. Had a terrible time getting the load down the barrel when I did. Gave it up before I broke something. Mebbe gave up too quick.

Over-powder wads are something I believe in. The Wonderwads are great, but I'm sorta conserving mine as I hear no one is making them now. I find a couple of lubed patches between the patched ball and the powder do about the same thing.

3f Goex at 90 gr., :hmm:. THAT I haven't tried at all. Been tempted to try Pyrodex P. Most anything that shoots well with RS seems to shoot better with P....if you've got the nerve to use it. I'm a little shy about loading anything faster than 2f/RS for heavy loads.

Real BP is getting hard to find around here. End of season, I usually stock up on Pyrodex when Wally World puts it on sale and then shoot it the following year.

Thanks for the load info, though. You can bet I'll give that a try in the 1-48" barrel.
Bob

 

[roundball]

3f Goex at 90 gr., :hmm:. THAT I haven't tried at all. Been tempted to try Pyrodex P. Most anything that shoots well with RS seems to shoot better with P....if you've got the nerve to use it. I'm a little shy about loading anything faster than 2f/RS for heavy loads.

Just to be clear, this load is from the range of powder charges in TC's published load data tables for each caliber...nothing home made about it, etc...and they were all just round ball loads, nothing heavy about them

 

[Donny]

I love the old T/C, but the shoots I go to are offhand. If I cut short the butt, installed a shotgun recoil pad, and shot it off the bench, maybe I could make the slow twist GM bbl work for me using the 90-100 gr load. I don't know if my shoulder could take it.

 

[MuzzleNut]

I put a new GM 54 drop in on my T/C Hawken. Went to the range this past Tuesday. Shot 80gr goex ffg with remington .530 gold balls and wally world pillow ticking lubed with T/C butter. I didn't know if I would be on the paper at 50 yards but to my surprise the first shot was a about an inch high and just a skosh to the left. 2nd shot was at 6:00 and in the white - caused by a too light set trigger. I adjusted the trigger pull to a little heavier - 3rd shot clover leafed the first. I adjusted my hold just a little and the 4th and 5th shots were over the X but still a little high. I made a one click adjustment on elevation and the 6th shot was in the X. I am plenty pleased with the GM barrell in 54 cal. :m2c:

 

[JOHN L. HINNANT]

Greeting Muzzlenut,

If you remove the barrel and tang from your stock, then drill and tap each side flat of the tang with a 10-24 thread and istall two headless 10-24 set screws, STOP! THIS IS GETTING TO BE A RUN-ON SENTENCE.

Anyway do that, and use the set screws to tighten the hook in the breech. By making this a solid one piece unit and eliminating all movement between the tang and barrel, you should see another big improvement in grouping accuracy.

My Santa Fe Hawkins did not have enough room to drill and tap, so I epoxied them together. Major improvement in repeatable grouping accuracy and zero holding.

GM barrels are one of the best buys out there today. Their IBS drop-ins allow a T-C owner to have a truely switch barrel rifle in a variety of calibers with a minimum of fuss.

Best regards and good shooting,

John L. Hinnant

If you are not an NRA Member, I am carrying your load.

 

[big bore 75]

I have never done that method , but if something has to be don glass bed the tang abd barrel, just remember to put enough release on the breech and tang, green mountain barrels are great for the money and many many matches have been won with them. bb75

 

[Nimrod]

Ha John do you have a picture of the 2 set screws in the tang? :what: Nimrod :thanks:

 

[Headhunter]

I shot my GM 50 Cal 1-70" last night. What a shooter. I knew this barrel would shoot before I put a cap on it. The inside of the barrel is S-L-I-C-K-!

50 Grains of Powder at 25 yards was not a ragged hole, It was 1 hole. Shot out to 75 yards with 90 Gains and was shooting less than 1". What a barrel.

I did bed the barrel with Accraglass Gel.

Headhunter.

 

[davy]

Here ya go .. this is a TC GM 50 cal tang/barrel mod that John Hinnant did for me on my TC Renegade a short while ago! I have not shot it yet.. but will very soon!

Davy

 

[JOHN L. HINNANT]

Greetings All,

Thank you Davy. The pics are very much appreciated.

Davy knows that I do not have the equipment or computer knowledge to put pictures on the forum and has come to my rescue before.

Most likely, he will have to again.

Best regards and good shooting,

John L. Hinnant

If you are not an NRA Member, I am carrying your load.

 

[big bore 75]

Hey that ain't a bad idea ,think I might do the same when I build that rigby that I'm thinking about. bb75

 

[ladysmithtrading]

John, Thanks for the idea! I'm restocking a t/c now with a pecatonica full stock and a gm barrel is on the way, gonna have to take it and the tang to my buddy the builder and have him do this for me, guess ill have to take the renegade along also!